This is a phase III, multicenter, open, active controlled, 1:1 randomized 28-week parallel group study with two treatment groups (HOE 901 and NPH human insulins). The study consists of up to a four-week screening phase, followed by a 28-week treatment phase. Visits will occur at Screen, Week 0 (Baseline), 1, 4, 8, 12, 20 and 28. On three occasions, subjects will be admitted for 24-hour plasma glucose profiles. These will occur at Baseline and at Weeks 8 and 28. The purpose of this study is to compare the efficacy and safety of HOE 901 with those of NPH human insulin. It will be performed in subjects with type I diabetes who are receiving multi-dose insulin therapy with NPH and regular insulins.